The present invention relates to a pump assembly.
Japanese Patent Application Unexamined Publication No. 2001-80498A discloses a pump apparatus including a pump body accommodated in a housing and fluid chambers disposed between the pump body and the housing. The fluid chambers include a low fluid pressure chamber, a high fluid pressure chamber, a high fluid pressure chamber and a low fluid pressure chamber which are arranged in this order in an axial direction of the pump body. These fluid chambers are separated from each other by O rings which are disposed between the adjacent fluid chambers.